1. Field of the Invention
The present invention relates to a multi-ply heat-insulating material in which a plurality of hollow cavities are formed and consisting of layers of non-metallic metallized supporting material.
As distinguished from a conventional heat-insulating material, of which the heat-insulating effect is due almost exclusively to the absorption of heat, in the case of heat-insulating material provided with metal layers the insulating action results essentially from the reflection of the heat radiation. Thus, for example, a flexible material having a symmetrical structure made of two plain plastics layers having sandwiched therebetween a separating layer in the form of a corrugated cellular material is already known (cf. U.S. Pat. No. 4,136,222), the opposite inner faces of the external plastics layers being provided with a mirror-like or specular reflection layer.
A known multi-ply construction element (German Pat. No. 835,522) consists of a plurality of superposed corrugated plastic films, of which the two external ones have their internal faces coated with a metal layer.
Now, however, systematic measurements conducted by the Applicant on various combinations and configurations of heat-insulating materials made of one or several layers proved that the heat carrying capacity of all the test samples was relatively high, when their metal layer or layers were directed towards the heat source or covered directly with another material, that nevertheless, with a fully predetermined arrangement of the metal layers quite surprisingly a reduction in the heat carrying capacity of the order of 30 to 100 percent could be obtained, in comparison with usual combinations of the otherwise identical materials.